Mass Extinctions Through History (Part 4)

What You'll Learn

Extinction occurs when the last member of a species dies. Mass extinctions have occurred several times in Earth's history, the most famous killing the dinosaurs 66 million years ago.

Key Words

heredity
allele

Materials Needed

paper
colored pencils
coins (for Punnett squares)
tape

Safety First

Be careful with scissors — ask an adult for help if needed.
Do not look directly at the sun or bright lights.
Clean up spills immediately to prevent slipping.

Steps

Step 1 — Read

Read the introduction and identify the main idea of this lesson.

Step 2 — Do

Extract DNA from a strawberry using dish soap, salt, water, and rubbing alcohol. Observe the stringy white substance—that's DNA!

Step 3 — Observe

Look for patterns in your observations.

Step 4 — Record

Make a graph or chart showing your results.

Check Your Understanding

Question 1

1 of 3

What is an allele?